Power monitoring systems monitor the flow of electrical power in circuits through a plant or other facility. In the POWERLOGIC system manufactured by the instant assignee, circuit monitors and power meters are dedicated to power monitoring, while other compatible devices collect additional equipment information from protective relays, circuit breakers, transformer temperature controllers, and panelboards. Electrical data, such as current, power, energy, waveforms, and equipment status, is passed over a data network to one or more personal computers. The personal computers run power monitoring application software that retrieves, stores, organizes, and displays real-time circuit information in simple, usable formats. The information collected and stored in a power monitoring system helps operate a facility more efficiently. The quality of the data depends upon the accuracy of the instrumentation and the usability of the display formats.
The power meter can replace conventional metering devices such as ammeters, voltmeters, and watt-hour meters while providing other capabilities not offered by analog metering. The power meter's true rms readings reflect non-linear circuit loading more than conventional analog metering devices. The power meter calculates the neutral current, which can assist in identifying overloaded neutrals due to either unbalanced single phase loads or triplen harmonics. Circuits can be closely monitored for available capacity by keeping track of the peak average demand current.
The power meter can provide a full complement of rms metering values to a metering display and/or via a standard communication port to a power monitoring and control system. The display is connected to the power meter with a communications cable and allows the user to view metering data and access meter setup and reset menus. Because the display can be mounted at a remote location relative to the power meter itself, the power meter can be installed in tight equipment spaces without sacrificing a convenient and affordable metering display.
One type of remote metering display includes a character-based display screen that presents power monitoring data such as voltage, current, power and energy. The display is remote from the power meter but is connected to the power meter via an RS-232 or other communications cable that provides both the power metering data and power to the display. By using several user interface buttons, a user can selectively navigate through defined data screens that present specific data. The remote metering display may be mounted on a front switchgear panel while the power meter itself is mounted within the switchgear. In fact, there may be several displays mounted on the same front switchgear panel.